A New Jersey man drowned at a bachelor party while playing a game of “Who can stay underwater the longest,” authorities said Tuesday.

Robert Zachary “Zack” Bunsa, 23, of Basking Ridge was at a home on Lake Sinclair in Georgia on Saturday with about a dozen other guests, including his brother, when the group started the contest.

“He was attempting to see how long he could hold his breath, and tragically, he drowned,” Baldwin County Sheriff’s Capt. Brad King told The Post. “I don’t know if it was the type of thing that was ongoing all afternoon or if it was a spur-of-the-moment type” game.

The group of 15 men didn’t realize Bunsa hadn’t gotten out of the water at first. Thinking he was already back at the house, they went up to find him, authorities said.

“He was missing for some time — over 7 minutes, at least — before they realized,” Cpl. Lynn Stanford told the Macon Telegraph.

Finally, one of the men back at the lake dove in to look for Bunsa and pulled him out of an area between 5 and 10 feet deep near the dock. Visibility in the lake is about 1 foot, Stanford said.

A law enforcement officer living nearby heard a call on the radio and responded to the dock, performing CPR for 10 to 15 minutes before EMS arrived.

A helicopter was called to airlift Bunsa for treatment — but he was already pronounced dead at the scene.

Bunsa was a graduate of Koinonia Academy in Plainfield, NJ, where he played on the high school’s basketball team. He worked at Urban Table Restaurant in Basking Ridge, a former employer of his, Lauren Rubio, told NJ.com.

“He was an awesome young man, we were blessed to have him,” Rubio said. “He always carried himself as a mature, strong person. We only have good things to say about him.”